1. Field of the Invention
The present invention relates to an automatic fire protection sprinkler, and in particular an extended coverage, horizontal sidewall sprinkler for light hazard occupancies.
2. Related Art
Fire protection sprinklers conventionally are connected to a conduit to receive pressurized fire-extinguishing fluid, such as water. A typical sprinkler has a base with a threaded portion for connection to the conduit and an output orifice to output the fluid to provide fire control and/or suppression. The output orifice is sealed by a seal cap, which is held in place by a release mechanism. The release mechanism is designed to release the cap under predetermined conditions, thereby initiating the flow of fire-extinguishing fluid. A typical release mechanism includes a thermally-responsive element, e.g., a frangible bulb or fusible link, and may also include a latching mechanism.
Certain conventional sprinklers have a pair of arms that extend from the base portion and meet at a hub portion to form a frame. The hub portion is spaced apart from the output orifice of the base portion and is aligned with a longitudinal axis thereof. The hub portion may have a set-screw configured to apply a pre-tension force to the release mechanism. A deflector may be mounted on the hub, transverse to the output orifice, to provide dispersion of the output fluid.
Fire protection sprinklers may be mounted on a fluid conduit running along a ceiling and may either depend downward from the conduit, which is referred to as a “pendent” configuration, or may extend upward, which is referred to as an “upright” configuration. Alternatively, a sprinkler may be mounted on a wall, a certain distance below the ceiling, which is referred to as a “horizontal sidewall” configuration. Horizontal sidewall sprinklers have an output orifice that is oriented so that the fluid is output horizontally and sprays onto an area to be protected in front and to the sides of the sprinkler. Such sprinklers may be mounted in a supporting cup with an escutcheon and cover, to provide a concealed configuration.
NFPA 13 (“Standard for the Installation of Sprinkler Systems,” National Fire Protection Association, Inc., 2002 Edition) classifies automatic sprinklers according to “occupancies,” which define requirements for sprinkler design, installation, and water supply requirements. Light hazard occupancies are defined as areas in which the quantity and/or combustibility of contents is low, and fires with relatively low rates of heat release are expected (NFPA 13, Section 5.2).
As described in Section 5.9 of UL 199 (“Standard for Automatic Sprinklers for Fire-Protection Service,” Underwriters' Laboratories, 11th Ed., Nov. 4, 2005), an “extended coverage” sprinkler for light hazard occupancies is a sprinkler intended: a) for use at greater than standard spacing; b) to open automatically by operation of a heat responsive element and releasing mechanism having a response time equal to or less than a standard response sprinkler used on standard spacings; c) to discharge water over a specified coverage area at a specified minimum water flow rate; and d) for use in light hazard occupancies as described in NFPA 13.
According to Section 8.9 of NFPA 13, extended coverage sidewall sprinklers for light hazard occupancies may have a spacing of up to 28 ft between sprinklers, as measured along the wall on which the sprinklers are mounted, and may cover an area of up to 400 ft2.